UC Davis researchers reported in a spring issue of the journal Science that neuronal activity
in the eye permits eye-specific connections to the brain, contrary to the conventional view of how connections
form between the optic nerves and the brain.

Early in development, retinal cells show activity long before eyes are exposed to light. At the same
time, optic nerves grow from the left and right eyes into the brain and form separate "eye-specific" layers
in a brain structure called the lateral geniculate nuclei, or LGN. Neuroscientists currently think that
the pattern of spontaneous activity is essential to "instruct" the formation of separate left and right
eye connections to the LGN.

Led by Leo M. Chalupa, professor of ophthalmology and neurobiology, UC Davis researchers Andrew Huberman,
Guo-Yong Wang, Lauren Liets, Odell Collins and Barbara Chapman in the Division of Biological Sciences
used an antibody coupled to a ribosomal toxin to perturb the activity of selected cells in the retina.
The retinal cells still show spontaneous activity, but in a random rather than a normal pattern. Surprisingly,
the axons of the optic nerve still grow into the brain normally and form normal layered LGN structures.
However, when all activity was completely blocked in the developing retina, the researchers found that
the normal separation of left and right eye connections did not occur.